Coupling



FIG. 1 is a front perspective view of one embodiment of a coupling showing our new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a top view thereof, the bottom view being identical;

FIG. 4 is a left side elevation thereof, the right side elevation being identical;

FIG. 5 is a front elevation thereof; and,

FIG. 6 is a rear elevation thereof.

The broken lines shown in the drawings form no part of the claimed design. 

We claim the ornamental design for a coupling, as shown and described. 